The electrical machines with a rotary superconducting winding located in the rotor incorporate a cryogenic cooling system of the winding. The cooling agent in this system is constituted by liquid helium cooled to 4.2.degree. K. A distinguishing feature of the process of conveying liquid helium is the possibility of the development of a two-phase flow due to evaporation of a certain part of the liquid caused by friction between the steady stream of the liquid and the rotating parts of the electrical machine.
During conveyance of the steady stream of liquid helium to the rotating parts of the electrical machine, the increased friction raises the vapour content in the mixture, the resistance to its movement and, as a consequence, the temperature of cryogen.
All these factors reduce the power and efficiency of the electrical machine.
Known in the prior art is a device for supplying cryogen to the rotary superconducting winding of a cryogen-cooled electrical machine (see U.S. Pat. No. 3,809,933 of May 7, 1974, U.S.A.).
Known in the prior art is an electrical machine with a cryogenic cooling system (see U.S. Pat. No. 3,809,933, May 7, 1974, U.S.A.).
In this machine, the device for delivering cryogen to a rotary superconducting winding comprises a pipe for delivering a steady stream of cryogen into the space of the electrical machine with the pipe being articulated along the axis of said machine. One end of said pipe is located with a clearance in a rotary chamber which flares out in the direction of cryogen flow, and the rotary chamber communicates with the space of the electrical machine accommodating its superconducting winding.
However, this cryogen-delivering device is not very effective because the stream of cryogen supplied from the pipe into the chamber has a high relative speed of collision with the chamber surface which leads to the formation of a considerable amount of vapour in the cooling agent or cryogen. This vapour is not expelled from the chamber and a large amount of vapor in the cryogen causes a nonequilibrium state of the cryogen and, in the long run, impairs the conditions of cryogen delivery to the superconducting winding and reduces the amount of supplied cryogen.
Besides, there develop convective vortices in the gap between the pipe and the rotary chamber which intensifies the inflow of heat to the cryogen.